Glow discharge lamp



Sept. 27, 1932. T. E. FOULKE GLOW DISCHARGE LAMP FiledDec. 19, 1928Patented Sept. 27, 1932 UNITED. STATES PATENT! OFFICE TED EUGENE FOULKE,OF NUTLEY, NEW JERSEY, ASSIGN'OR TO GENERAL ELILGilItllICl VAPOR LAMPCOMPANY, OF HOBOKENT, NEW JERSEY, CORPORATION OF NEW JERSEY GLOW mscmenLAMP Application filed December 19, 1928. Serial 110. 327,073.

The present invention relates to electric lamps of the negative glowtype and has for its object to produce a lamp of this type having longcommercial life, low voltage starting characteristics, where desired,maintenance of gas purity within the envelope and the attainment of thefull corona over the area of the electrode or electrodes and to aconstruction lending itself to quick exhaust thus facilitating rapidshop production of the device. i Various other objects and advantages ofthe invention will be obvious from the following description of one formof lamp embodying the invention or from an inspection of theaccompanying drawing and the invention also consists in certain new andnovel features of the structure and combinations of parts hereinafterset forth and claimed.

In the accompanying drawing there is shown for purposes of illustrationone form of lamp embodying the invention in which Fig. 1 is a sectionalelevation of my new lamp,

Fig. 2 is a view of the electrode assembly taken along the line 2-2 ofFig. 1,

Fig. 3 is a sectional view of said lamp taken at: right angles to Fig.1, Fig. 4: is a view of the insulating block supporting the electrodesshowing in dotted lines the cavities and holes for introducin the stemand leads for the electrodes and mechanical supports of the variousparts, i

Fig. 5 is a view of a semi-cylindrical electrode and v Fig. 6 is asectional view of an alternative embodiment of my invention.-

In the drawingthe sealed envelope 1 has' mounted therein a stem 2 havingsealed there- 40 through lead wires 3 and 4. Above the stem 2 is mountedan insulating block 5 of lavite, porcelain, glass or other suitableinsulating material, and in the event the member 5 is a solid block,holes 6 and 7 (see Figs. 3 and 4) are drilled. therein to accommodatethe lead wires 3 and 4.

The envelope 1 has a filling of gas, such as gas of the argon group, orhydrogen or a source of gas or vapor such as mercury, mercury alloy,lithium, cadmium, caesium or the operatinggconditions in the interior ofthe responding increase in the life of the lamp,

by reducing the proportion of neon to the minimum which will still givethe characteristic neon color, say 5% or less. I

For operating on regular commercial circuits such as those of 110-220volts a resistance (not shown) is necessary in the lamp circuit and thisis preferably mounted in the base of the lamp. On the outside of theblock 5 are mounted the semi-cylindrical electrodes 9 and 10 which areidentical in'configuration, the end of each of said electrodes 9 and 10extending over'the topof the block 5. The tabs 11 and 12 which extendupwardly from the ends of said electrodes 9 and 10, respectively, areconnected by welding to the respective lead wires 4 and 3. Theelectrodes 9 and 10 are stamped from 5 mil sheet nickel, but othermetals such as iron, copper, brass, zinc, aluminum. magnesium, calciumor any metals found uitable may also be used.

In the alternative structure shown in Fig. 6 the insulating block 5 istubular, the leads passing through the center thereof, and the ends ofthe electrodes are crimped u on said insulating block 5 to hold them inp ace. I

The lamp is provided with a getter and keeper material for maintainingthe desired device. y locating this getter on the electrodes and by usinfor this purpose a metal or metallic oxide 0 lower atomic weight than vthe electrode material a dual function may be performed by this getter,since in eddition to maintaining the operating condltlons it will alsoserve to materially reduce thes uttering of the electrode material. In tose cases where nickel electrodes are used a paint of aluminum andmagnesium pieces is preferthat the tendency to sputter is greater atthis point than on the sides of the electrodes. The result of thisconstruction is a great decrease in the sputtering of the electrodes,the useful life of the lamp being accordingly increased. A means ofsupporting these electrodes will be described later which practicallyeliminates any remaining tendency to sputter.

Each of the electrodes 9 and 10 in these devices is provided with asmall piece of mag-.

nesium 15 welded at acorner of the electrode on the inner surfacethereof so that in the finished lamp the magnesium pieces 15 are atopposite sides of the block 5 and this material or equivalent is presentin the lamp, and it appears to serve as a getter and keeper .but itsprincipal function here, which is controlled by the treating process infinishing the lamp, is that of activating the surface of the electrodeto lower the starting and operating:

voltages of the lamp. For any given set of starting and peratingvoltages, of course, it will be understood that other materials such ascalcium, barium, strontium, lithium, potassium, rubidium and caesium oralloys thereof may be used in place of magnesium or any combinationtherewith and when desired compounds of the alkali metal or alkalineearth metals are also suitable,-it being understood, of course, that inthe finishing or treating of the lamp that the compounds are reduced toprovide the metal surfaces desired which may be accompanied by applyingheat to an electric discharge as is now well understood.

It will be noted that the block 5 is provided on opposite sides thereofwith channels 16 and that the electrodes 9 and 10 are mounted on theblock 5 so that the edges of the elec trodes project slightly beyond theedges of the channels 16 but with an intervening space between the edgesof the electrodes themselves. lIhave discovered that this particularconstruction lends itself readily to the starting into operation of thedevices at lower voltages than if the channels 16 were not present atthis point. It appears that where insulation is present between theelectrodes whether they be of the rounded or flat type that if theinsulation is parallel with the 1 edges of the electrodes and moreparticularly whenin contact therewith that difliculty is encountered instarting and maintaining operation on desired voltages and sputtering atthis point is encountered. It will be understood, of course, that ifdesired the channel can be continued across the top of the block 5 but Iprefer to mount a getter material on the top of the device as previouslydescribed,

respect to the space between the electrode edges and by removing thesurface from the immediate neighborhood of the charged space, there isless tendency to attract positive ions from the space and thus it ispossible to start a discharge across the space at lower appliedpotentials and at the same time, as less positive ions are drawn fromthe space there is less disintegration of the insulating material due toionic bombardment thereof.

In addition to the foregoing elements of my device I provide a getter 17of the keeper type, and commonly called a keeper which comprises anysubstance that will render innocuous any gaseous impurities evolvedduring normaloperation of the device. For this purpose I preferably uselime and red phosphorous mixed with amyl acetate or water to forin'apaint and the mixture is painted on the stem 2 and serves, after heatingto remove the amyl acetate or water, to absorb those gases developed inthe operation of the device which do not appear to be taken up by themetallic getters and keepers above referred to.

The envelope 1 can be made of lead glass, or other soft glass, or leadboro-silicate or pyrex or G702P, or of quartz. Lamps made according tomy invention can be started on regular commercial circuits such as thoseof 110 and 220 volts but it is desired that a lamp be provided that Willoperate efficiently on 110 volts as this is the most common type ofcircuit in use. Due to the combination of elements above described mylamp will start on such low voltage circuits and will operate for a longcommercial life without substantial depreciation in operatingcharacteristics or light giving properties.

The gas'is fed into the lamp at 36 mm. pressure although good resultswill be obtained between pressures ranging from 30 mm. to

While I have shown and described and have pointed out in the annexedclaims certain novel features of the invention it will be understoodthat various omissions and substitutions and changes in the forms, partsand deresult, so long as the general effect is tubular,

andthe terms used are intended to cover such other forms.

It is now well known that these lamp devices may be used as sources ofillumination or as voltage regulators or negative characteristic gridleaks to be used in conjunction with currents such as are used intelephone and telegraph systems and to the rapid mod'- ulation of lightsources and electric currents and in devices for producing periodiclight or current fluctuations. a

I claim:

1. In an electriclamp of the negative glow type, in combination, a gastight envelope containing gas capable of luminous discharge upon thepassage of an electric current, a

cylindrical electrode support of refractory material having twolongitudinal grooves oppositely disposed therein and twosemi-cylindrical metallic electrodes whose edges overlap the edges ofsaid grooves.

2. In an electric lamp of the negative glow type, in combination, a gastight envelope containing'gas capable of luminous discharge upon thepassage of an electric current, a. cylindrical electrode support ofrefractory material having two longitudinal grooves oppositely disposedtherein, two semi-cylindrical metallic electrodes whose edges overlapthe edges'of said grooves and a getter on the BXtGIIOI end of at leastone electrode.

'3. In an electric lamp of the negative glow type, in combination, a gastight envelope containing a mixture of helium and neon, a cylindricalelectrode support of refractory material having two longitudinal groovesoppositely disposed therein and twosemi-cy lindrical metallic electrodeswhose edges overlap the edges of said grooves.

.4. In an electric lamp of the negative glow type, in combination, a gastight envelope containing a mixture of helium and neon,

a cylindrical electrode support of refractory material having twolongitudinal grooves oppositely disposed therein, two semi-cylindricalmetallic electrodes whose edges over lap the edges of said groove, and agetter on the exterior end of at least one electrode.

5. In an electric lamp of the negative glow type, in combination, a gastight envelope containing a mixture of helium, noon and argon, acylindrical electrode support of refractory material having twolongitudinal" grooves oppositely disposed therein, and twosemi-cylindrical metallic electrodes whose edges overlap the edge ofsaid grooves. Y

6. In an electric lamp of the negative glow type, in combination, a gastight envelope containing a mixture of helium, neon, and argon, acylindrical electrode support of refractory material having twolongitudinal grooves oppositely disposed therein, two semi-cylindricalmetallic electrodes whose edges overlap the edges of said grooves,-and

a getter on the exterior electrode.

7. In an electric lamp of thenegative glow type, in combination, a gastight envelope containing gas capable of luminous discharge upon thepassage of an electric current, a cylindrical electrode support ofrefractory material having two longitudinal grooves opend of .at. leastone positely disposed therein, two semi-cylin drical metallic electrodeswhose edges overlap the edges of said grooves, a getter on the vexterior end of at'least one electrode and a quantity of activatingmaterial on at least one electrode.

8. In an electric lamp of the negative glow type, in combination, a gastight envelope containing gas capable of luminous discharge upon thepassage of an electric current, a cylindrical electrode support ofrefractory material having two longitudinal grooves oppositelydisposed'therein, two semi-cylindri- -cal metallic electrodes whoseedges overlap the edges of said grooves, a getter on the ex-' terior endof at least one electrode and a keeper within said envelope. 4

9. In an electric lamp of the negative glow type, in combination, a gastight envelope containing a mixture of rare gases, a cylindricalelectrode support of refractory material having two longitudinal groovesoppositelydisposed therein, two semi-cylindrical metallic electrodeswhose edges overlap the edges of said grooves, a getter on the exterior,end of at least one electrode, a quantity of activating material on atleast one electrode, and a keeper applied adjacent. to the lead-ins ofsaid envelope.

10. In an electric lamp of the negative glow .upon the passage of anelectric current, an. insulating body and two electrodes therein,

an edge of one of said electrodes being adj acent to an edge of theother, said electrodes being adjacent to and conforming to the shape ofsaid insulating body except'at said adjacent edges, said edges being atan ap precia-bly greater distance from said insulatin g bodythantheremainderof said electrodes. 12. In an electric lamp of thenegative glow type, in combination, a gas tight envelope containing gascapable of luminous discharge upon the passage of an electric current,and

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nickel -electrodes therein, at least one of said electrodes having acoating of magnesium and aluminum. V Signed at Hoboken in the county ofHudson and State of New Jersey this 18th day of December A. D. 1928.

TED E. FOULKE.

